This chapter focuses specifically on the activities and questions that are involved in the generation of data to support the registration and approval of a drug candidate. The data generated in early stage studies provide confidence for deciding whether to advance a drug into more complicated and expensive trials in specific patient populations. During middle stage development it is critical to begin to characterize the dose-response relationship for efficacy and safety endpoints in the selected population. Late stage confirmatory clinical trials often utilize a broader study population than was studied during early development. Besides the general scientific and medical literature, there are several important sources of information that can help with the strategy for clinical development programs and the design of specific trials and their questions. The FDA provides access to guidance documents that outline regulatory requirements related to the development of drugs and devices.